Rock drill



J. E. @ENFER mg@ w33? ROCK DRILL Filed May 22, 1930 2 Sheets-Sheet 2INVENTOR WM a M Patented ug. 22, 1933 UNITED STATES PATENT OFFICECleveland Rock Drill Company,

Cleveland,

Ohio, a Corporation of Ohio Application May Z2, 1

6 Claims.

This invention relates to fluid actuated machines of the rock drilltype, and specically to an improved valve mechanism for distributingmotive fluid to such machines. Y

One object of this invention is to effect the distribution of motivefluid to the opposite ends of a cylinder of a fluid actuated machinewith a minimum pressure drop between the fluid supply line and theworking chambers to thereby increase the eiciency of the machine.

Another object is to supply motive luid to the opposed working chamberswith an appreciable lag therebetween, to insure the delivery of the fullforce of the piston hammer to the drill steel or tool.

Other objects are to provide an improved simplied valve construction; toarrange the elements of the valve to obtain rapid opening and closing ofthe iluid ports; to provide a novel lubricating means for a fluidactuated machine; and to arrange the parts of the machine in such amanner as to facilitate and simplify the assembly thereof.

Other objects relating to details of construc- D tion and economies ofmanufacture will appear hereinafter.

In the accompanying drawings, which illustrate a preferred embodiment ofthe invention:

Fig. 1 is a vertical medial section through a rock drill constructed inaccordance with this invention and showing the relation assumed by theparts near one extreme oi the piston travel.

Fig. 2 is a similar View showing the relation assumed by the parts nearthe opposite extreme of the piston travel.

Referring to the drawings, the improved machine is housed within acylinder 5, a front head 6, and a back head 7 secured together in theusual manner by side rods (not shown). A piston hammer 8 is slidablymounted within the cylin er and has a riiled axial opening slidablyreceiving a riiied bar 9 which cooperates in the usual manner with arotation mechanism 10. The latter is supported between the cylinder 5and back head 7 in a sealing chamber which consists of a plate 11 seatedon an annular shoulder 12 near the end of the cylinder, a ring 13 seatedon the plate 12, and a plate 14 seated on an internal shoulder in thering 13. The riled bar 9 passes through a central aperture in the plate11 into the cylinder 5. The piston 8 is provided f with a splined stem15 which cooperates in the usual manner with a chuck 16 to rotate thetool or drill steel 17.

The wall of the cylinder 5 is formed with a 930. Serial No. 454,549

hollow cylindrical enlargement 18 which houses the valve mechanism. Asleeve 19 forming one element of the valve is slidably mounted in thecentral portion of the enlargement 18 and has its opposite ends bearingin the bores 20 and 21 60 oi the enlargement. intermediate the bores 20and 21 is an expanded opening 22 spaced from the sleeve 19 to provide alubricant reservoir 23.

The bore 2O terminates in an annular recess 24 the entire inner side ofwhich opens into an annular recess 25 in the cylinder 5. Beyond therecess 24 the enlargement 18 is formed with a bore 26 slightly larger indiameter than the bore 20 and receiving a bushing 27 having a 'flange 28seated upon the end of the enlargement 18. A sleeve 29 is slidablymounted within the bush ing 27 and is provided with a flange 30 bearingin the bore 26.

At thn opposite end of the enlargement 18 the bore 21 terminates in anannular recess 31 opening into a recess 32 in the cylinder 5. A bore 33beyond the recess 31 receives a plug 34, and a sleeve 85 having a flange36 isV slidable inthe plug 34 and the bore 33.

The sleeves 19, 29, and 35 are axially aligned and constitute thedistributing valve for controlling the flow of motive iluid to theopposite ends of the cylinder. The ends of the sleeve 19 are arranged toabut the adjacent ends of the sleeves 29 and 35 to interruptcommunication between the interior of the sleeves and the respectiverecesses 24 and 31, and are accordingly provided, in the preferredembodiment of the invention, with packing 52 made of rubber or l othersuitable material. The packing 52, which is retained in recesses in theends of the sleeve 19, seats against the sleeves 29 and 35 to provide anefficient seal and also cushions the movement of the sleeve. If desired,the packing can be omitted in which case the ends of the sleeves must bemachined with extreme accuracy in order to prevent leakage of the motiveiluid.

Packing 37 of any suitable type is disposed between the ange 28 of thebushing 27 and the back head 7. When the drill is assembled the head 7first engages the packing 37 and compresses the same. The ring 13 ismade of sufcient height to engage the head 7 and prevent contact thereofwith the cylinder 5. TheV side rods or other securing means are Vthendrawn down tightly to form a fluid tight seal between the head 7 and thepacking 37 and between the head and the ring 13, leaving a space 38between thev head and the cylinder 5. The working chambers of themachine are thereby completely sealed and the va ious parts are rigidlymaintained in position.

A source of motive fluid is connected with the supply duct 39 in theusual manner and is controlled by the throttle valve of any suitabletype. A port 4G leads from the duct 39 through the packing 37 totheinterior of the bushing 27. An exhaust port 41 is formed in the wall ofthe cylinder 5 and is arranged substantially closer to the r s 32 thanto the recess 25. A pair of cro d conduits 42 and 43 open through thewall ci the cylinder at spaced points on opposite sides ot the exhaustport 41. The conduit 42 opens into an annular space 44 between theflange 36 and the plug 34, and the conduit 43 opens into a similarannular space 45 between the flange 30 and the bushing 27.

The adjacent end faces of the sleeves 19 and 29 are ester ally groovedtc :form pressure areas 46 and 47, respectively. Similar pressure areas43 and 49 are formed on the adjacent end faces of the sleeves 19 and 35.The sleeves 29 and 35 are consti-ucter with internal diameters smallerthan the internal diameter or the sleeve 19 to form interior pressureareas 59 and 5l on the sleeves 29 and 35, respectively. These pressureareas 59 5l are suiliciently larger than the areas of the ends oi thesleeves 29 and 35 remote from the shove 19 to provide constant pressurestending to hold the sleeves 2S and 35 away in the sleeve 19 when thepressures in the annular spaces 44 and 45 are less than the sure withinthe sleeves.

The lubricant reserv ir 23 is provided with filling opening at anyconvenient point in the wall of the enlargement 18, and is arranged tosupply lubricant to the valve and piston. The lubricant passes betweenthe sleeve 19 and the bores 29 and 21 capillary action, and is entrainedin the motive fluid through a small port 46 formed in the sleeve 19. Thepulsations in the motive iluid created by operation of the machine forcelulrcant through the port 45', the reservoir 23 be g full of lubricant,the lubricant exudes through the passage 46 onto the inner walls oi thesleeve 19 the compressed air, passing through the sleeve 19, carrieslubricant into the cylinder the usual manner.

In operation, assumeVV the parts are in the position shown in l. Whenthe throttle valve is opened, air flows through the duct 39 and thepassage 4 between the ends of the sleeves 19 and 29, and through theannular recess 24 into the upper end of the cylinder 5. The valveelements are held in position by the pressure of the incoming air actingagainst the lower end of the sleeve 29 and flange 30 and the upper endof the sleeve' 19 and against the pressure area 5l, the upper side orthe flange 30 being open to atmosphere through the conduit 43 and port41 and the pressure areas 48 and 49 being open to atmosphere through therecess 31 and port 41. The pressure of the air acting against the upperside of the piston 8 forces the same downwardly to deliver a blow to thedrill steel 17. The piston is shown in Fig. 1 just after the beginningof this downward stroke.

As the piston moves downwardly the upper edge thereof uncovers theconduit 42, admitting air to the space 44 to act against the under sideof the flange 33. This flange is of such area that the pressurethereagainst overcomes ecess the pressure acting against the upper endof the sleeve 19 and the area 51, and the sleeves 19 and 35 aretherefore moved upwardly until the upper end of the sleeve 19 seatsagainst the lower end of the sleeve 29, thereby cutting oi all flow ciair to the cylinder.

The piston continues its downward movement under inertia and theexpansion of the air in the upper end of the cylinder and the exhaustport 41 1's then uncovered. At this time air is being compressedslightly in the lower end of the cylinder, this compression having begunvhen the lower end of the piston passed the exhaust port 41. Thisslightly compressed air acts against the pressure areas 48 and 49, butwith insufficient force to change the relation oi the valve elements. Asthe air exhausts from the upper end oi the cylinder, the pressure in thespace 44 is relieved through conduit 42 and exhaust port 41. The airwhich has been compressed in the lower end oi the cylinder acts againstthe pressure area 49, and together with the constant pressure acting onthe pressure area 51, nieves the sleeve 35 downwardly. At the same timethe compression in the lower end oi the cylinder acts on the pressurearea 48 to hold the sleeve 19 in its raised position. Live air from thesupply line thereupon ilows between the ends of the sleeves 19 and 35 tothe lower end of 'he cylinder 5 just as the pisto delivers its blow tothe drill steel 17. i

At this time the parts are in the position illustrated in Fig. 2. Thesleeve 29 is held in its raised position by the live air acting againstthe pressure area 59, and the sleeve 19 is held in raised position bythe pressure against the lower end thereof. As the piston moves upwardlyunder the influence of 'the live air adinitted te the lower end or^ thecylinder, the conduit 43 is uncovered and air hows therethrough toy thechamber 45 to act upon the upper side ci the flange 39 and force the twosleeves 19 and 29 downwardly, cutting off all flow oi air to thecylinder. When the lower edge of the piston uncovers the exhaust port 41the pressure in the space 45 is relieved through conduits 43 and exhaustport 41, allowing the sleeve 29 to move upwardly under the iniluence ofthe constant pressure acting on thepressure area 59 together with thecome pression in the upper end of the cylinder acting against thepressure area 47. The force against the pressure area 46 holds thesleeves 19 and 35 in their lowermost positions and as a consequence airis again admitted to the upper end of the cylinder between the ends ofthe sleeves 19 and 29.

j The exhaust port 41 is located substantially closer to the lower endof the piston stroke than to the upper in order that live air will bead- .mitted to the lower end of the cylinder after the piston hasdelivered its blow to the drill steel, and will be admitted to the upperend in ample time to check the upward movement of the piston and preventthe same from striking plate 11.

It will be evident that the air passages to both ends of the cylinderare relatively large and unobstructed and that as a consequence thepressure drop through the valve is relatively small. This permitsefcient operation of the drill on low air pressures and also makespossible a more rapid action and the delivery of a more powerful blow tothe drill steel. Since the downward stroke oi the pistonV is notcushioned by the incoming air the full force of the momentum acquired bythe piston is delivered to the drill.

It will also be evident that a relatively small movement of the valvemembers produces a relatively large opening. The pacliings 37 and 52, inaddition to sealing the air passages, serve as cushions for the valvemembers during their movement and decrease the Wear on the parts. Ifdesired, a packing similar to the packing 37 may be employed beneath theplug 34. The lubricant reservoir 23 insures free action or" the valveand in addition provides a convenient means for lubricating the entiremachine.

While the foregoing description is necessarily of a detailed characterit is to be understood that the specific terminology employed is not tobe construed as restrictive or limiting, and it is to be furtherunderstood that various rearrangements of parts and modiiications may beresorted to without departing from the scope or spirit of the inventionas claimed herein.

I claim:

l. In a rock drill having a cylinder and a piston reciprocable therein,a distributing valve including a sleeve, means for admitting motivefluid into said sleeve, conduits communicating with the opposite ends ofsaid sleeve and the opposite ends of said cylinder, means forinterrupting communication between said sleeve and said conduits, andmeans responsive to pressure within the cylinder developed by movementof the piston within the same for maintaining said sleeve out ofcommunication with one of said conduits while establishing communicationof said sleeve with the other conduit.

2. In a iluid actuated machine having a cylinder and a pistonreciprocable therein, a valve for controlling the flow of fluid to theopposite ends or" said cylinder, said valve including a pair of sleevesdisposed in abutting relation, means for admitting' motive iiuid intosaid sleeves, and means responsive to pressures developed in saidcylinder by said piston moving within said cylinder adapted to separatesaid sleeves to admit motive uid to one end of said cylinder.

3. In a uid actuated machine having a cylinder and a piston reciprccabletherein, a valve for controlling the flow of iiuid to the opposite endsof said cylinder said valve including a pair of movably mounted abuttingsleeves, means for admitting motive iiuid into said sleeves, meansactuated by pressure iluid for moving both said sleeves to interrupt theiiow of fluid to one end of said cylinder, and means actuated bypressure developed in said cylinder by the movement of the pistonthereinfor separating said sleeves to admit motive fluid to the other end ofthe cylinder.

4. In a iiuid actuated machine, a hollow valve casing, and valve meansincluding a sleeve slidable in said casing, said casing being enlargedintermediate the ends of said sleeve to form therewith a lubricantreservoir, and to lubricate said slidable sleeve, said sleeve having anopening therethrough for the passage of lubricant into the interior orsaid valve means.

5. In a iluid actuated machine having a cylinder and a pistonreciprocable therein, a fluid passage communicating with both ends ofthe cylinder, valve means formed of three elements slidably disposed insaid passage, means actuated by motive fluid for moving said elements tointerrupt the ow of motive fluid alternately to the opposite ends of thecylinder, means responsive to drop of pressure within said cylinder tomove two of said elements apart and means responsive to compressionwithin said cylinder to maintain said last mentioned elements in theiroppositely moved position.

6. In a fluid actuated machine having a cylinder and a pistonreciprocable therein, a fluid passage communicating with both ends ofthe cylinder, a sleeve slidably disposed in said passage and a sleeveslidably disposed in said pasi sage on each side of said first namedsleeve providing three sleeves in all, pressure surfaces on oppositesides of each of said sleeves, there being a conduit communicatingcentrally with the cylinder and with the pressure surface on one of saidend sleeves, there being a second conduit communicating centrally withsaid cylinder and with the pressure surface on one side of the other endsleeve, the iluid passage communicating with the ends of the cylinderalso serving to communicate with the pressure sur` face on the oppositesides of said end sleeves and with the pressure surface on said irstmentioned sleeve and means for admitting motive fluid to the interior ofsaid sleeves.

JOHN E. RENFER.

